Yeah, surely, interconnecting side sticks and providing stick shakers or haptic buzzers on them is gonna save Airbusses from pilots stalling them.
Lets ASSUME the combination of interconnect and sidesticks prevents ONE 100 plus passenger aircraft going splat in say 10 years.
Please compute the cost- benefit ratio OF NOT doing it and provide it to the few survivors or families of those who did not survive along with your message of condolence.
Why would anyone NOT want to use or have available ALL three senses ( light- sound- physical ) when the fit hits the shan ?
Granted adding such is not a cure all- and never will be absolute, but it would add a few nines to the human error probibility equation.